Monitoring is the process of continuously observing a system to detect performance issues or failures. It involves collecting and analyzing metrics, logs, and events to ensure that applications, infrastructure, and networks are functioning correctly. Monitoring helps in identifying bottlenecks, predicting potential problems, and maintaining system health. Tools like Prometheus, Grafana, Nagios, and Zabbix are widely used for monitoring purposes, providing dashboards, alerts, and visualizations that help operators maintain optimal performance and availability. Effective monitoring is crucial for proactive issue resolution and ensuring a high-quality user experience.